Do this by aria-owning the sidebar into the header wrapper. aria-owned subtrees get added as the last child after all other child elements that are in the DOM. This way, if a sidebar tab is activated, the aside element now is inserted in a position following the tabs, before the main messages list. The association for screen readers is therefore more logical. This has no bearing on the DOM order or CSS properties. aria-owns simply rearranges the accessibility tree.
Fixes vector-im/riot-web/issues/11319
Signed-off-by: Marco Zehe <marcozehe@mailbox.org>
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